1. Field of the Invention
The present invention relates to a method for preparing a flavor-containing sheet used for a smoking article, a flavor-containing sheet for a smoking article prepared by the method, and a smoking article comprising the same.
2. Description of the Related Art
If a volatile flavor component such as menthol is added to cut tobacco in a solution state, the flavor component is dissipated in a long-term storage and the flavor effect does not last. In order to solve such a problem, various reports have been made.
Patent Documents 1 and 2 disclose that a flavor component is placed in the filter part of a cigarette with the flavor component coated with a natural polysaccharide to suppress the volatilization and dissipation of the flavor component; and the coated favor component is crushed by pressing it to release the flavor at the time of smoking. Patent Document 3 discloses that a flavor component is placed in the filter part of a cigarette with the flavor component coated with a water-soluble matrix such as dextrin to suppress the volatilization and dissipation of the flavor component; and the water-soluble matrix is dissolved by the moisture in the mainstream smoke to release the flavor at the time of smoking. Thus, when the flavor component is placed in the filter part which is a non-burning part of the cigarette, there is a time lag until the flavor is tasted because the flavor is released by pressing the filter part at the time of smoking or dissolving the water-soluble matrix by the moisture in the mainstream smoke.
On the other hand, Patent Documents 4 to 6 report an example in which a flavor component is placed in a burning part, that is, cut tobacco or a cigarette paper which wraps it.
Patent Document 4 discloses that a cigarette paper which wraps tobacco filler is coated with a flavor material in which the flavor component is incorporated into the three-dimensional network of the glucan molecules. The cigarette of Patent Document 4 has a good flavor-retaining property since the flavor component is fixed and retained with incorporated into the three-dimensional network of the glucan molecules. However, the flavor component is present in the glucan molecules in a relatively small amount (20 wt % or less). Accordingly, in the case of the flavor component which requires a relatively large amount to be added, such as menthol, the blending amount of the flavor material to the cigarette becomes high.
Patent Document 5 discloses that “a stabilized flavor substance which is stable up to 180° C.” is prepared by mixing a liquid flavor with a carrageenan sol; dropping the mixture into an ionic solution (a solution containing potassium ions) to prepare a particulate gel; and drying the gel in the air. However, the method of Patent Document 5 requires long periods of time and large facilities in order to prepare a large amount of the material because the granular gel is dried in the air. In addition, the method requires the addition of a metal ion (gelling accelerator) in order to form a gel.
Patent Document 6 reports that a sheet containing a flavor component with coated with a gel of polysaccharide is produced by drying a slurry containing the flavor component such as menthol and the polysaccharide; and the sheet is cut and the cut pieces is added to cut tobacco. According to the report, it takes a week to dry the slurry at 40° C.
As described above, various reports have been made as technique for suppressing the volatilization of the flavor component, but there is still a need for a easy method of preparing a flavor material having a further improved flavor-retaining property after storage.